He is the son of Thalia King and Abraham Thorn and the older brother of Julia King; he is also the half-brother of Alexandra Quick, as well as at least four other older half-sisters that he knows of, including Lucilla, Drucilla and Valeria White from Thorn's second marriage, and Livia Pruett and another daughter of Thorn's first marriage. Maximilian's parents were married in the late 1980's, and later divorced. He lived on the King family ranch of Croatoa in the Roanoke Territory.
During the 2008-2009 school year, he took part in the MASE Program, spending the term at the Charmbridge Academy along with Martin Nguyen, Tybalt Franklin, Pierce Prince, Adelaide Speir, and Beatrice Hawthorne. He and his fellow Stormcrows were introduced to the Charmbridge students by Dean Grimm during the start-of-term assembly.
In September, he helped in breaking up a fight between Anna Chu and Tomo Matsuzaka, restraining Alexandra Quick after she had disarmed the other two girls. After Matsuzaka, Quick and Chu were assigned to the Junior Regimental Officer Corps in punishment, King was particularly hard on Chu and Quick.
He later joined the Mors Mortis Society along with Matsuzaka, Quick, Torvald Krogstad, Stuart Cortlandt, Darla Dearborn, and Angelique Devereaux. During the first meeting of the schoolyear, he witnessed Sue Fox summon a spirit through a portal in the stone chamber below the basements of Charmbridge; after the meeting, he emphatically instructed Quick to stay away from the Society.
Following the meeting, he became even more critical and overbearing toward Quick and Chu, culminating in a Saturday of wand and broom drills during which he raced Quick through the forest surrounding the Academy. Quick crashed into a tree, and King was publicly dressed down by Colonel Shirtliffe, losing a stripe.
In November of 2008, Maximilian revealed to Quick their mutual paternity after rescuing her from being tortured by John Manuelito during a Mors Mortis Society meeting. In the days following, he told her that she had at least five other half-siblings, including his younger sister Julia. He revealed that he came to Charmbridge Academy hoping to be invited to join the Mors Mortis Society, because the Wizard Justice Department had recruited him to infiltrate the MMS in the hopes that he could discover their Dark Convention contacts. His own personal motivation for working with the Department to break up a Dark Arts coven was to use the success as a means of advancing his own career as well as lifting the stigma of the Thorn name.
He also told Alexandra that of his friends, only Nguyen and Hawthorne, who had been his friends since sixth grade, knew who his father was. After confessing his familial relationship to Quick, he treated her and Chu with less hostility during JROC training; he also began revealing information to Alex regarding their family history. He, Nguyen and Hawthorne later invited Quick to accompany them in a wizard-duel, which, Nguyen explained, was "dueling without all the bowing and timeouts and rules." King demonstrated an impressive aptitude for unrestricted offensive and defensive combat, defeating both Nguyen and Hawthorne in a two-on-one contest, and began training Quick in such tactics.
"Alexandra noticed that all of the BMI students looked bemused, except for one, a tall, handsome, broad-shouldered boy with straight hair as dark as Martin's. He was studying Alexandra and the other Charmbridge students next to her, rather than staring at Darla, who was still babbling."